前言

RecyclerView 的使用我就不再多说，接下来的几篇文章主要说一下 RecyclerView 的实用小功能，包括列表宫格的切换，吸顶效果，多布局效果等，今天这篇文章就来实现一下列表宫格的切换，效果如下

一、数据来源

数据来源于知乎日报API，采用 okhttp+retrofit 组合方式请求获取，网络请求没有进行二次封装，只是简单请求数据源，对于有需求的用户自行进行封装修改。

二、使用步骤

1.引入库

  //万能适配器implementation 'com.github.CymChad:BaseRecyclerViewAdapterHelper:2.9.50'//卡片布局implementation 'androidx.cardview:cardview:1.0.0'//图片加载implementation 'com.github.bumptech.glide:glide:4.9.0'//json解析implementation 'com.alibaba:fastjson:1.2.61'//标题栏implementation 'com.github.goweii:ActionBarEx:3.2.2'// 只引入ActionBarEximplementation 'com.github.goweii.ActionBarEx:actionbarex:3.2.2'// 引入ActionBarCommon/Search/Super，依赖于ActionBarEximplementation 'com.github.goweii.ActionBarEx:actionbarex-common:3.2.2'

2.获取数据

使用如下 URL 进行数据请求：API 使用的 HTTP Method 均为 GET

https://news-at.zhihu.com/api/3/news/hot

响应实例：

{"recent": [{"news_id": 3748552,"thumbnail": "http://p3.zhimg.com/67/6a/676a8337efec71a100eea6130482091b.jpg","title": "长得漂亮能力出众性格单纯的姑娘为什么会没有男朋友？","url": "http://daily.zhihu.com/api/2/news/3748552"}]
}

根据实例生成实体类 NewsListBean 实现序列换接口 Serializable

public class NewsListBean implements Serializable {private String date;private List<Recent> recent;public String getDate() {return date;}public void setDate(String date) {this.date = date;}public List<Recent> getRecent() {return recent;}public void setRecent(List<Recent> recent) {this.recent = recent;}public static class Recent implements Serializable {private String news_id;private String thumbnail;private String title;private String url;public String getNews_id() {return news_id;}public void setNews_id(String news_id) {this.news_id = news_id;}public String getThumbnail() {return thumbnail;}public void setThumbnail(String thumbnail) {this.thumbnail = thumbnail;}public String getTitle() {return title;}public void setTitle(String title) {this.title = title;}public String getUrl() {return url;}public void setUrl(String url) {this.url = url;}}
}

写一个接口类用来管理 API ,可以单独放在一个文件夹下

public interface ApiUrl {@GET("/api/4/news/hot")Call<NewsListBean> getPic();}

3.主要代码

1 activity_main.xml

这里使用了三方库 ActionBarEx 实现了沉浸式标题栏，使用了系统的 ProgressBar 实现请求加载框

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"><per.goweii.actionbarex.ActionBarExandroid:id="@+id/abc_main_return"android:layout_width="match_parent"android:layout_height="wrap_content"android:background="#14a4fb"app:ab_autoImmersion="false"app:ab_bottomLineColor="#f3f3f3"app:ab_bottomLineHeight="0dp"app:ab_statusBarColor="#00000000"app:ab_statusBarMode="dark"app:ab_statusBarVisible="true"app:ab_titleBarHeight="50dp"app:ab_titleBarLayout="@layout/top" /><androidx.recyclerview.widget.RecyclerViewandroid:id="@+id/zh_lv"android:layout_width="match_parent"android:layout_height="match_parent"android:layout_below="@+id/abc_main_return" /><ProgressBarandroid:id="@+id/progressbar"style="@style/Base.Widget.AppCompat.ProgressBar"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_centerInParent="true"android:visibility="gone" />
</RelativeLayout>

2 zh_item_layout.xml

列表子布局 ,采用 CardView 卡片布局

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"android:id="@+id/zh_card_View"android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_marginLeft="@dimen/dp_10"android:layout_marginTop="10dp"android:layout_marginRight="@dimen/dp_10"android:layout_marginBottom="@dimen/dp_10"app:cardBackgroundColor="#ffffff"app:cardCornerRadius="10dp"app:cardElevation="10dp"app:cardPreventCornerOverlap="true"app:cardUseCompatPadding="false"><RelativeLayoutandroid:layout_width="match_parent"android:layout_height="120dp"><RelativeLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"android:background="@color/transparent"><ImageViewandroid:id="@+id/news_image"android:layout_width="70dp"android:layout_height="70dp"android:layout_centerVertical="true"android:layout_margin="10dp"android:elevation="2dp"android:scaleType="fitXY" /><TextViewandroid:id="@+id/news_title"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_centerVertical="true"android:layout_marginStart="10dp"android:layout_marginTop="10dp"android:layout_marginEnd="10dp"android:layout_toEndOf="@id/news_image"android:ellipsize="end"android:maxEms="15"android:singleLine="true"android:textColor="@color/black"android:textSize="20sp" /></RelativeLayout></RelativeLayout></androidx.cardview.widget.CardView>

3 zh_grid__item_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"android:id="@+id/zh_card_View"android:layout_width="match_parent"android:layout_height="180dp"android:layout_marginLeft="@dimen/dp_10"android:layout_marginTop="10dp"android:layout_marginRight="@dimen/dp_10"android:layout_marginBottom="@dimen/dp_10"app:cardBackgroundColor="#ffffff"app:cardCornerRadius="10dp"app:cardElevation="10dp"app:cardPreventCornerOverlap="true"app:cardUseCompatPadding="false"><LinearLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"android:background="@color/transparent"android:gravity="center"android:orientation="vertical"android:padding="@dimen/dp_10"><LinearLayoutandroid:layout_width="match_parent"android:layout_height="0dp"android:layout_weight="3"><ImageViewandroid:id="@+id/news_image"android:layout_width="match_parent"android:layout_height="match_parent"android:scaleType="fitXY" /></LinearLayout><LinearLayoutandroid:layout_width="match_parent"android:layout_height="0dp"android:layout_weight="1"android:gravity="center"><TextViewandroid:id="@+id/news_title"android:layout_width="wrap_content"android:layout_height="wrap_content"android:ellipsize="end"android:maxEms="8"android:singleLine="true"android:textColor="@color/black"android:textSize="20sp" /></LinearLayout></LinearLayout></androidx.cardview.widget.CardView>

4 NewsListAdapter 适配器

public class NewsListAdapter extends BaseQuickAdapter<NewsListBean.Recent, BaseViewHolder> {public NewsListAdapter(int layoutResId, @Nullable List<NewsListBean.Recent> data) {super(layoutResId, data);}@Overrideprotected void convert(@NonNull BaseViewHolder helper, NewsListBean.Recent item) {helper.setText(R.id.news_title, item.getTitle());String img = item.getThumbnail();ImageView newsImage = helper.getView(R.id.news_image);Glide.with(mContext).asBitmap().load(img).diskCacheStrategy(DiskCacheStrategy.ALL).into(newsImage);helper.addOnClickListener(R.id.zh_card_View);}}

5 BaseActivity 基类

public abstract class BaseActivity extends AppCompatActivity {@Overrideprotected void onCreate(@Nullable Bundle savedInstanceState) {Window window = getWindow();// 5.0以上系统状态栏透明if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);window.getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN| View.SYSTEM_UI_FLAG_LAYOUT_STABLE | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);window.setStatusBarColor(Color.TRANSPARENT);}if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {// 全屏显示，隐藏状态栏和导航栏，拉出状态栏和导航栏显示一会儿后消失。window.getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_STABLE// | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN| View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION// | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION// | View.SYSTEM_UI_FLAG_FULLSCREEN| View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);} else {// 全屏显示，隐藏状态栏window.getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_FULLSCREEN);}}//预防软键盘挡住输入框getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN);//禁止横屏setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);super.onCreate(savedInstanceState);}}

6 MainActivity 主要代码

这里主要通过一个 boolean 值 isGrid 来判断是否切换状态来加载不同的布局，以及布局管理器来达到实际效果

public class MainActivity extends BaseActivity {private RecyclerView zhLv;private ProgressBar proBar;private NewsListAdapter adapter;private List<NewsListBean.Recent> mList = new ArrayList<>();private static final int REQUEST_EXTERNAL_STORAGE = 1;private static String[] PERMISSIONS_STORAGE = {Manifest.permission.READ_EXTERNAL_STORAGE,Manifest.permission.WRITE_EXTERNAL_STORAGE};private ImageView menuBtn;private LinearLayoutManager layoutManager;private ImageView btnImg;private LinearLayout backLayoput;public static void verifyStoragePermissions(Activity activity) {int permission = ActivityCompat.checkSelfPermission(activity,Manifest.permission.WRITE_EXTERNAL_STORAGE);if (permission != PackageManager.PERMISSION_GRANTED) {ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,REQUEST_EXTERNAL_STORAGE);}}private boolean isGrid = false;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);verifyStoragePermissions(MainActivity.this);initView();initData();menuBtn.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {switchLayout();}});}private void switchLayout() {if (isGrid) {layoutManager = new LinearLayoutManager(this);adapter = new NewsListAdapter(R.layout.zh_item_layout, mList);zhLv.setAdapter(adapter);} else {layoutManager = new GridLayoutManager(this, 2);adapter = new NewsListAdapter(R.layout.zh_grid__item_layout, mList);zhLv.setAdapter(adapter);}zhLv.setLayoutManager(layoutManager);isGrid = !isGrid;}private void initView() {zhLv = findViewById(R.id.zh_lv);proBar = findViewById(R.id.progressbar);menuBtn = findViewById(R.id.btn_main_menu);btnImg = findViewById(R.id.btn_main_menu);backLayoput = findViewById(R.id.btn_back_layout);backLayoput.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {finish();}});layoutManager = new LinearLayoutManager(MainActivity.this);zhLv.setLayoutManager(layoutManager);adapter = new NewsListAdapter(R.layout.zh_item_layout, mList);zhLv.setAdapter(adapter);}private void initData() {proBar.setVisibility(View.VISIBLE);Retrofit retrofit = new Retrofit.Builder().baseUrl("https://news-at.zhihu.com/")//设置数据解析器.addConverterFactory(GsonConverterFactory.create()).build();ApiUrl apiUrl = retrofit.create(ApiUrl.class);Call<NewsListBean> call = apiUrl.getPic();call.enqueue(new Callback<NewsListBean>() {@Overridepublic void onResponse(Call<NewsListBean> call, Response<NewsListBean> response) {List<NewsListBean.Recent> recent = response.body().getRecent();if (response.body() != null && recent.size() > 0) {try {mList.addAll(recent);adapter.setNewData(mList);proBar.setVisibility(View.GONE);} catch (Exception e) {String message = e.getMessage();e.printStackTrace();}}}@Overridepublic void onFailure(Call<NewsListBean> call, Throwable t) {Log.e("mmm", "errow " + t.getMessage());}});}}